CRAYSAT-1917: Fix jinja2 rendering of boot_sets data in sat bootprep

Make the following fixes:

- Remove the `boot_set` property from `BaseInputItem`. It is not appropriate
  there, and it is redundant with `boot_sets` property that already exists in
  the `InputSessionTemplate`
- Modify the `jinja_rendered` decorator to recursively render more complex
  objects like lists and dictionaries. I think this is safe, but we should
  consider any edge cases more carefully.
- Remove the now unnecessary code that does a one-off Jinja2 rendering of
  `rootfs_provider_passthrough` in the `boot_sets`.

Could still use unit test enhancements that test this new ability to render
fields in the boot_sets.

Test Description:
Tested on a simple bootprep input file that used a variable in the
`rootfs_provider_passthrough` field of a boot set in a BOS session template.

sat/cli/bootprep/input/base.py

@@ -108,14 +108,25 @@ def wrapper(self, *args, **kwargs):
         # Default to no additional context if not set
         context = getattr(self, 'jinja_context', {})
 
-        try:
-            return self.jinja_env.from_string(unrendered_result).render(context)
-        except SecurityError as err:
-            raise error_cls(f'Jinja2 template {unrendered_result} for value '
-                            f'{func.__name__} tried to access unsafe attributes.') from err
-        except TemplateError as err:
-            raise error_cls(f'Failed to render Jinja2 template {unrendered_result} '
-                            f'for value {func.__name__}: {err}') from err
+        def render_object(obj):
+            """Render an object with the given context."""
+            if isinstance(obj, str):
+                try:
+                    return self.jinja_env.from_string(obj).render(context)
+                except SecurityError as err:
+                    raise error_cls(f'Jinja2 template {obj} for value '
+                                    f'{func.__name__} tried to access unsafe attributes.') from err
+                except TemplateError as err:
+                    raise error_cls(f'Failed to render Jinja2 template {obj} '
+                                    f'for value {func.__name__}: {err}') from err
+            elif isinstance(obj, dict):
+                return {key: render_object(value) for key, value in obj.items()}
+            elif isinstance(obj, list):
+                return [render_object(item) for item in obj]
+            else:
+                return obj
+
+        return render_object(unrendered_result)
 
     return wrapper
 
@@ -242,11 +253,6 @@ def name(self):
         # items that inherit from BaseInputItem.
         return self.data['name']
 
-    @property
-    def boot_set(self):
-        """Return the full boot_sets dictionary."""
-        return self.data.get('bos_parameters', {}).get('boot_sets', {})
-
     def __str__(self):
         # Since the name can be rendered, and when unrendered, it does not need
         # to be unique, just refer to this item by its index in the instance.

sat/cli/bootprep/input/session_template.py

@@ -98,6 +98,7 @@ def configuration(self):
         return self.data['configuration']
 
     @property
+    @jinja_rendered
     def boot_sets(self):
         """dict: the boot sets specified for the session template"""
         # the 'bos_parameters' property is required, and 'boot_sets' is required within that
@@ -186,12 +187,6 @@ def get_create_item_data(self):
             boot_set_api_data.update(boot_set_data)
             api_data['boot_sets'][boot_set_name] = boot_set_api_data
 
-            # Fetch full boot sets
-            boot_sets = self.boot_set
-            # Render the rootfs_provider_passthrough using Jinja2
-            rendered_rootfs = self.jinja_env.from_string(
-                        boot_sets[boot_set_name]['rootfs_provider_passthrough']).render(self.data)
-            api_data['boot_sets'][boot_set_name]['rootfs_provider_passthrough'] = rendered_rootfs
         return api_data
 
     def get_image_record_by_id(self, ims_image_id):